Hi, I would be very grateful if anyone could post a picture or a drawing of a standard SY250 flywheel, ideally with the dimension of the outer width of the flywheel. Mine has been machined to make it lighter, the overhang has been removed plus an additional 6 or 7mm milled away so I'm planning to spot weld a 14mm wide ring to end up with a total flywheel weight of 3.1kg. It would be very useful to see what the flywheel looked like before being machined. Many thanks for your help.

It can be done but its a pain, why dont you just buy a TYZ rob the flywheel and sell it on. thats what i did. Dont be tempted to buy the motor for sale on ebay, as i already robbed that one years ago.

I'm planning to spot weld a 14mm wide ring to end up with a total flywheel weight of 3.1kg

Spot weld??????

If you electric weld (induce a strong, fluctuating magnetic field) near the magnets, they might not be magnets when you are done.

If you flame weld near (heat up) the magnets they might not be magnets afterwards.

I suggest two alternatives:

Take the existing ring off, add your extra ring by welding and then refit it to the flywheel

Take the existing ring off and fit a new ring the size you want to the flywheel